Personal feelings, of course, are some greetings or greetings, and then naturally start a story or joke, of course, the content should be related to the popular science knowledge you want to talk about, so as to arouse your interest in listening and speaking, and then start a formal lecture. Of course, some humorous words can also be interspersed in the middle, provided that they are related to the theme and the last is the end. If there are examples in the process or they can be related to real life, you must bring them up, so as to leave a deep impression on the listeners and make your lecture successful.